Which head

[Tiger]

Hello
Just about to part strip my 1936 Ruby ARR
ENGINE Has the brass set pin above the web so expecting 3 bearing crank ?
It has the LC head is this correct for that engine.
Or was it possible to have either head originally?
Is their much advantage to the HC head ?
Thanks in anticipation 
Regards
           Tim

[Ruairidh Dunford]

If your engine is three bearing then I think it would have originally come with a high compression head - these do work well.

However, if a previous owner suffered plug oiling or main bearing thump, they 'may' have fitted the low compression head to suppress the effects of these problems.

P.s. the 'brass' pin you mention is normally steel, in my experience, and locates in the centre camshaft bush to stop it rotating/moving.

[Tiger]

Many thanks Ruairidh.
Just about to remove the sump and have a look at the bottom end.
My vehicles history is unknown.
Also appears to have been very badly treated.
So lots of wrongs to right
Hey Ho that’s life.
Agatha (my A7) Now in a happy place
Tim

[Chris KC]

I only once drove with a LC head, which someone kindly lent me to get to an event while my own head was under repair. I was glad to hand it back though - I was accustomed to getting 60 or 70mph out of my Nippy and she suddenly wouldn't go over 40...

[Reckless Rat]

The easy way to tell if you've got the High Compression or Low Compression head is to look at the water outlet to the top hose. On the low comp head it is longditudinal and held in place by one single central stud. The later, high comp head is located transversely with a two stud fixing. The spark plugs on the LC head are 18mm and the later head 14mm.
High Compression head here:

[garryruck]

Just came across this high compression head and wondered what spark plugs are best,

[Bob Kneale]

I always use Champion L86C plugs on my High Compression head in the Ruby 3 bearing engine On my 2 Bearing engine with a similar head, I've used the same, but the engine feels harsh, and I'll be going back to the Low Compression arrangement with Champion  18mm H6 plugs which feels better even though the power output is a little lower.
Cheers
Bob

[Derek Sheldon]

Reckless, almost correct but I think that there are a few HCvheads out there with LC water off takes

[garryruck]

Bob
Have you got a supplier for the H6 Champion plugs?

[Zetomagneto]

Reckless, almost correct but I think that there are a few HCvheads out there with LC water off takes

I’ve never seen one!